Carburetor



B. WALKER Aug. 15, 1967 CARBURETOR 2 Sheets-Sheet 1 Filed April 1, 1965 700 INTAKE THROTTLE CL 0550 VALVE OPE/V SENS/N6 VAL VE VALVE OPE/V ABOVE I000 REM.

70 INTAKE MAN/FOLD CLOSED CLOSED WHEN BELOW KE Y 5 W/ TCH THR 0 7' TLE PREDEEW/l/ED cwsso ENG/NE srsza United States Patent O 3,336,012 CAREURETOR Brooks Walker, 1280 Columbus Ave, San Francisco, Calif. 94133 Filed Apr. 1, 1965, Ser. No. 444,572 7 Claims. (Cl. 261-26) This invention pertains to improvements in a device for wetting the manifold after a fuel off operation, such as high speed decelerations, particularly when said shut off involves a device for sucking or removing the fuel from the float chamber to cut off the supply of fuel to the idle and main jets and by dropping the level of the fuel in the float bowl, the fuel being rapidly returned to the normal level in the float bowl for normal engine power operation when the engine speed drops below a predetermined speed or when the throttle is opened. This returns the fuel above the intake to the main and idle jets for normal power operation along with an extra injection of fuel to the intake of the engine driving the return of the fuel to the float bowl.

One such device for sucking the fuel out of the float bowl is shown in my application, Ser. No. 419,418, entitled Carburetor, filed Dec. 18, 1964, now Patent No. 3,256,870, issued June 21, 1966.

With such a device there is a short period of lean operation of the engine when the fuel is returned to the float bowl due to two things; one is the low level of the fuel in the float bowl as it rises from just covering the intake to the main and idle jets until it reaches the normal level in the float bowl, even though this may only take one-half second to refill the bowl. The other is the time taken to establish a normally wet intake manifold after operation with the fuel off and a dried out intake manifold.

This invention attempts to reduce this period of lean operation at the start of reestablishing the normal full flow from the carburetor to the engine by providing an extra injection of fuel during the return of the fuel to the float bowl. One method of accomplishing this in this invention is by the use of a Pitot tube pickup to utilize the velocity of the fuel in returning to the bowl to provide an injection of fuel into the intake manifold either on the engine side of the throttle butterfly or above the throttle butterfly in the carburetor.

If injected above the butterfly in a downdraft carburetor, the injection can discharge into the carburetor main passage at a point above the level of the fuel in the float chamber, in which case no anti-percolating or antisiphoning device would be required. Such fuel will be drawn on into the engine in the inevitable leakage past a closed butterfly if the fuel flow is reestablished when the engine speed drops below a predetermined speed on continued closed throttle decelerations to establish idling and to prevent stalling.

If during the deceleration the operator decides to apply power, such as to pass another vehicle, he will open the throttle from a fuel off dried out manifold condition and such extra injection will reduce the short lean period of operation, help wet the manifold more quickly, and to some extent act as an accelerator pump. However, such a device alone will not act as an accelerator pump from a part throttle non-dried out condition to a wider open throttle more power condition, as fuel is not flowing into the float bowl past the pitot pick up as the fuel has not been withdrawn from the float bowl during such operations of cruising at power, then accelerating. During such operations a normal accelerator pump may be necessary. A normal accelerator pump may even aid in wetting the manifold when suddently opening the throttle from a high speed closed throttle deceleration.

Another object of this invention is to use the velocity of the fuel returning to the float bowl to get the extra full injection during each return of fuel operation.

Another object is to inject this extra fuel into the path of the air and fuel to idle while they enter on the engine side of the throttle butterfly with anti-siphon provisions in the extra fuel delivery.

Another object is an improved circuit for controlling the suck out of the fuel from the float bowl.

Other objects will be pointed out in the accompanying specification and claims.

I have illustrated my invention in the accompanying drawings, in which:

FIG. 1 is a side elevation view, ing one form of the invention.

FIG. 2 is a diagrammatic view of the portion of a circuit for controlling the suction to the suck out diaphragm with a solenoid operated vacuum control valve.

FIG. 3 is a side view, partly cut away, partly diagrammatic, of another form of the invention.

In all figures like numbers of reference refer to corresponding parts.

I have shown a carburetor 10 mounted on an engine 9 with intake manifold 6. The carburetor has a float 7 in chamber or bowl 11 operating a needle valve 12 to control the fuel flowing in through pipe 13.

A suck out diaphragm controlled mechanism in housing A includes a diaphragm 20 forced downwardly by spring 21. Diaphragm 20 is enclosed on one side by dished housing member 22 and the other side by flat plate 23. Line 24 connects a chamber 19 (between the lower side of diaphragm 20 and the flat plate 23) to passage 25, which leads into the float chamber 11, its housing 18 being secured thereto by bolts 26. Thus the chamber 19 may be considered as an auxiliary chamber of the carburetor fuel reservoir. Line 27 goes from a chamber 28 above the diaphragm 20 to a speed sensing valve B that turns on the suction from line 28 to line 27 and closes a bleed when the engine speed is above a predetermined speed, such as 1000 rpm. and closes the suction control valve from line 28 to line 27 and opens a bleed when the engine is below such predetermined speed. The bleed in valve B is easily overcome by the suction flow from line 29 as controlled by valve C which is open when the throttle is closed with its bleed closed and vice versa. A somewhat similar construction is shown in my co-pending application, Ser. No, 404,592, entitled, Vehicle Engine Control System, filed Oct. 19, 1964, or in my application, Ser. No. 427,649, entitled Fuel Feeding Device, filed Jan. 25, 1965. A control of suction somewhat similar to that shown in the Mallory, U.S. Patent No. 2,395,748, entitled, Degasser for Internal Combustion Engine, filed Feb. 26, 1946, may be used to control the suck out of the fuel by the use of a speed senser controlled bleed and throttle closed bleed to provide suction to operate a fuel shut off such as suck out diaphragm 23.

Other controls of the suction to control the suck out of the fuel, such as a solenoid valve operated by throttle and speed sensing switches, could be used in connection with this extra fuel feed on return of the fuel to help wet the intake manifold when power is required after a deceleration operation. This is shown in FIG. 2, in which valve 50 is operated by solenoid 52 which operates a two-faced valve 51. Valve 51 is urged to close opening 54 from engine suction line 53 to spring 56 when solenoid 52 is not energized. When solenoid 52 is energized, valve 51 is pulled down to close bleed 55 and allow flow from line 53 past port 54 to line 27 and on to operate diaphragm 20 to suck the fuel out of bowl 11 for fuel off decelerations.

A circuit to operate the solenoid partly cut away, show- 52 may include a 3 throttle controlled switch T which is closed when the throttle is closed and a second speed sensing controlled switch G in series which is closed when the engine is below a predetermined speed of rotation. Any other suitable circuit may be used.

When the fuel is withdrawn against the action of spring 21 from the bowl 11 in a suck out operation as when the diaphragm 29 has been raised by suction from line 27, the fuel will basically be out of the bowl 11' and below the intake to the passage 34 leading to the transfer port 31 and the idle needle valve 32 (see FIG. 3) and also below the intake to the passage 35 going to main jets 36 so there will be no fuel available when the fuel is out of the float bowl, such as during high speed decelerations when the throttle valve 8 is in the idle or closed position. The float may be held up by suction from line 27a to diaphragm motor D which lifts up on wire 37 in FIG. 3 or 38 in FIG. 1 during such decelerations.

When the vacuum is cut off, atmosphere is admitted to line 27 and spring 21 will push diaphragm downwardly returning the fuel to the float bowl 11 rapidly and returning the float 7 to normal operation. Pitot pick up 40 will induce fuel under pressure through lines 41 and 41a and squirt fuel from orifice 42 into the carburetor main air passage from where it will enter in the intake manifold 6 by going around the edges of the butterfly 8 in the idle or closed deceleration position, as shown in FIG. 1.

On deceleration at higher speeds when the engine 15 operating with the fuel sucked out of the float bowl 11 and then the throttle is opened suddenly as for passing another car or coming to a hill, etc., atmospheric pressure will be admitted through line 27 due to switch T opening, deenergizing solenoid 52 so spring 56 can move valve 51 up to close port 54 and open bleed 55. The diaphragm will move down promptly through action of spring 21 causing -a rapid flow of fuel through line 24 toward the float bowl 11. Fuel will be picked up by pitot tube (from the velocity of fuel flowing to the bowl) and injected into the main air passage 6 through orifice 42 which will assist in wetting the intake manifold which was dried out partially or completely during the fuel off or dry float chamber 11 operation. This action of fuel from orifice 42 plus the normal idle and main jet operation will establish a wet normal engine manifold quickly and with less engine stumble than if such extra fuel from orifice 42 were not employed.

If operating during deceleration with a tightly closed butterfly it may be desirable to inject or introduce the extra fuel on the engine side of the throttle butterfly 8. To do this a construction as shown in FIG. 3 could be used where the fuel picked up by Pitot tube 40 during the rush of fuel back to the float bowl 11 (as when the engine speed drops below the predetermined level, such as 1000 r.p.m.), and will be picked up by Pitot tube 40 discharged from pipe 45 and orifice 44 and then be sucked through passages 46 and 46a to enter the intake manifold 6 through port 47 along with the air and fuel to idle through passage 4% on the engine side of the closed throttle 8, the idle fuel entering through port 30a. The opening between outlet 44 and passage 46 prevents siphon action from tube 45 to the lower port 47 when the engine is running or stopped as the area of port 44 is open to the atmosphere by bleed hole 60.

Other means of withdrawing the fuel from the float chamber may be used with this invention which uses the velocity of fuel in establishing fuel flow to the idle and main jets to give an extra shot of fuel to the manifold to help wet it more quickly and reduce the short lean period the engine goes through after a fuel off operation to a fuel on operation.

I have illustrated my invention in these various forms; however, many other variations may be possible within the scope of this invention.

To those skilled in the art to which this invention relates many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and description herein are purely illustrative and are not intended to be in any sense limiting.

I claim as my invention:

1. A carburetor for an internal combustion engine including in combination a float bowl, an auxiliary chamber, a fluid path between said float bowl and said auxiliary chamber, a main air passage through said carburetor, means for automatically transferring fuel from said float bowl to said auxiliary chamber during high speed closed throttle operation of said engine, other automatic means for returning fuel from said auxiliary chamber to said float bowl when said throttle is opened, and automatic means for injecting extra fuel into said main air passage at the times when said fuel is being automatically returned to said float bowl.

2, A device as defined in claim 1 wherein said last mentioned automatic means includes a velocity pick up from the flow rate of said fuel flowing through said fluid path between said auxiliary chamber and said float bowl.

3. A device as defined in claim 1, further comprising means adapted to receive a portion of the fuel which is being returned as aforesaid to said float bowl before it enters said float bowl and conduct it to said main air passage, thereby providing said extra fuel.

4. A device as defined in claim 3, wherein said means to receive a portion of the fuel which is being returned to said float bowl are adapted to derive motive force from the fuel stream flowing to said float bowl and to impart such motive force to said extra fuel,

5. A device as defined in claim 4, wherein at least one element of saidmeans to receive a portion of the fuel which is being returned to said float bowl is adapted to perform as a Pitot pick up.

6. Internal combustion engine having a throttle valve and fuel supply means including a float bowl normally operable while said throttle valve is closed to deliver a predetermined quantity of idle fuel to said internal combustion engine; said internal combustion engine further comprising means adapted to shut off said idle fuel during a period of deceleration, means to restore said idle fuel supply upon termination of said period of deceleration and means adapted to augment the delivery of idle fuel to said internal combustion engine in response to said restoration of the idle fuel supply, said shut off means comprising a pump and means for operating the pump to withdraw the fuel from the float bowl, and said augmenting means comprising a conduit by-passing the float bowl for conducting fuel from the pump to the engine.

7. Internal combustion engine according to claim 6 wherein said means to restore said idle fuel comprises said pump, a valve operable in response to a predetermined engine speed, and means operable by said valve for energizing the pump.

References Cited UNITED STATES PATENTS 2,551,719 5/1951 Ball 261-34 2,824,725 2/ 8 Dietrich.

2,937,014 5/1960 Klaber 261-72 3,254,638 6/1966 Walker et a1. 26l41 X HARRY B. THORNTON, Primary Examiner.

T. R. MILES, Assistant Examiner. 

1. A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE INCLUDING IN COMBINATION A FLOAT BOWL, AN AUXILIARY CHAMBER, A FLUID PATH BETWEEN SAID FLOAT BOWL AND SAID AUXILIARY CHAMBER, A MAIN AIR PASSAGE THROUGH SAID CARBURETOR, MEANS FOR AUTOMATICALLY TRANSFERRING FUEL FROM SAID FLOAT BOWL TO SAID AUXILIARY CHAMBER DURING HIGH SPEED CLOSED THROTTLE OPERATION OF SAID ENGINE, OTHER AUTOMATIC MEANS FOR RETURNING FUEL FROM SAID AUXILIARY CHAMBER TO SAID FLOAT BOWL WHEN SAID THROTTLE IS OPENED, AND AUTOMATIC MEANS FOR INJECTING EXTRA FUEL INTO SAID MAIN AIR PASSAGE AT THE TIMES WHEN SAID FUEL IS BEING AUTOMATICALLY RETURNED TO SAID FLOAT BOWL. 